Image forming apparatus

Abstract

An image forming apparatus includes a plurality of image bearing members bearing latent images, image forming units for forming the latent images on the image bearing members, developing units for developing the latent images on the image bearing members, a transport belt for transporting a transfer member on which images of different colors developed by the developing units are successively transferred as the transfer member is transported, and image pickup elements, arranged obliquely to a main scan direction of the image forming units and located on a downstream of a most downstream one of the image bearing members along a direction in which the transport belt transports the transfer member. The image pickup elements detect as image information transmitted or reflected light quantity distributions of regions which include marks transferred on the transport belt from the image bearing members. The image forming apparatus further includes a correction unit for detecting correction quantities from error quantities of marks transferred from the image bearing members other than a reference image bearing member with respect to a reference mark transferred from the reference image bearing member based on the image information detected by the image pickup elements, and correcting positions of the latent images formed on the image bearing members other than the reference image bearing member depending on the correction quantities.